Synthesize this session's findings into a ranking of candidate verticals by the
one thing that actually gates cold email: a reliable public bulk source of
deliverable emails. Tier 1 (email native): FCC, FMCSA. Tier 2 (one free hop):
healthcare ORG NPIs (already harvested 63k verified), SEC/OTC corporate. Tier 3
(domain-scrape): FMC OTI, state business entities by trigger. Tier 4 (phone/mail
only, NOT email): CLIA (0.3% match proven), EPA RCRA, individual NPIs.
